HP Serviceguard Previewing the Effect of Cluster Changes, Change to the Cluster Configuration

Table 14 Types of Changes to the Cluster Configuration (continued)

Change to the Cluster Configuration Required Cluster State

Change the designation of an existing interface from HEARTBEAT_IP to STATIONARY_IP, or vice versa

Change an interface from IPv4 to IPv6, or vice versa

Reconfigure IP addresses for a NIC used by the cluster

Change NETWORK_FAILURE_DETECTION parameter (see “Monitoring LAN Interfaces and Detecting Failure: Link Level” (page 69))

Change NETWORK_AUTO_FAILBACK parameter

Change NETWORK_POLLING_INTERVAL

If removing the NIC from the system, see “Removing a LAN or VLAN Interface from a Node” (page 300).

Cluster can be running. See “Changing the Cluster Networking Configuration while the Cluster Is Running” (page 297).

Cluster can be running. See “Changing the Cluster Networking Configuration while the Cluster Is Running” (page 297)

Must delete the interface from the cluster configuration, reconfigure it, then add it back into the cluster configuration. See “What You Must Keep in Mind” (page 298). Cluster can be running throughout.

Cluster can be running.

Cluster can be running.

Cluster can be running.

Change IP Monitor parameters: SUBNET,	Cluster can be running. See the entries for these parameters
IP_MONITOR, POLLING TARGET	under “Cluster Configuration Parameters ” (page 109) for more
	information.
Change MEMBER_TIMEOUT and	Cluster can be running, except in CVM environment; see the
AUTO_START_TIMEOUT	NOTE below this table.
Change Access Control Policy	Cluster and package can be running.
Change capacity and weight parameters.	Cluster can be running.
	A change that would cause a running package to fail will trigger
	a warning, giving you a chance to cancel (unless you use
	cmapplyconf -f).

NOTE: If you are using CVM or CFS, you cannot change MEMBER_TIMEOUT or

AUTO_START_TIMEOUT while the cluster is running. This is because they affect the aggregate failover time, which is only reported to the CVM stack on cluster startup. You also cannot change the quorum configuration while SG-CFS-pkgis running.

Previewing the Effect of Cluster Changes

Many variables affect package placement, including the availability of cluster nodes; the availability of networks and other resources on those nodes; failover and failback policies; and package weights, dependencies, and priorities, if you have configured them. You can preview the effect on packages of certain actions or events before they actually occur.

For example, you might want to check to see if the packages are placed as you expect when the cluster first comes up; or preview what happens to the packages running on a given node if the node halts, or if the node is then restarted; or you might want to see the effect on other packages if a currently disabled package has package switching enabled, or if a package halts and cannot restart because none of the nodes on its node_list is available.

Serviceguard provides two ways to do this: you can use the preview mode of Serviceguard commands, or you can use the cmeval (1m) command to simulate different cluster states.

Alternatively, you might want to model changes to the cluster as a whole; cmeval allows you to do this; see “Using cmeval” (page 294).

292 Cluster and Package Maintenance